The protest was held on Saturday as North Korea marked the 69th anniversary of the country’s founding.

Nagasaki suffered an atomic bombing toward the end of World War Two. The attack occurred on August 9th, 1945. A group of survivors and others hold an event to remember the bombing on the 9th of every month at the city’s Nagasaki Peace Park.

About 80 people, including survivors of the atomic bombing and high school students, took part in Saturday’s protest.

Koichi Kawano, who heads a group of survivors, says he wants to urge the Japanese government to do more to discourage Pyongyang from conducting nuclear tests.

Another participant, Sachiho Mizoguchi, is one of the high school students who ask people to sign a petition calling for the abolition of nuclear weapons. She said she took part in the sit-in to protest against the North’s nuclear tests.

Eiji Okumura, a survivor of the atomic bombing, says North Korea conducted a nuclear test after the United Nations took a step toward the creation of a nuclear-free world by adopting a treaty that banned nuclear weapons. Okamura said he cannot tolerate the North’s latest nuclear test, and he wants to express his anger through the sit-in.